1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Joshua Henderson <joshua.henderson@microchip.com>
4  * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
5  */
6 #include <asm/mach-pic32/pic32.h>
7 #include <asm/fw/fw.h>
8 #include <asm/setup.h>
9 
10 #include "pic32mzda.h"
11 #include "early_pin.h"
12 
13 /* Default early console parameters */
14 #define EARLY_CONSOLE_PORT	1
15 #define EARLY_CONSOLE_BAUDRATE	115200
16 
17 #define UART_ENABLE		BIT(15)
18 #define UART_ENABLE_RX		BIT(12)
19 #define UART_ENABLE_TX		BIT(10)
20 #define UART_TX_FULL		BIT(9)
21 
22 /* UART1(x == 0) - UART6(x == 5) */
23 #define UART_BASE(x)	((x) * 0x0200)
24 #define U_MODE(x)	UART_BASE(x)
25 #define U_STA(x)	(UART_BASE(x) + 0x10)
26 #define U_TXR(x)	(UART_BASE(x) + 0x20)
27 #define U_BRG(x)	(UART_BASE(x) + 0x40)
28 
29 static void __iomem *uart_base;
30 static int console_port = -1;
31 
32 static int __init configure_uart_pins(int port)
33 {
34 	switch (port) {
35 	case 1:
36 		pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
37 		pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
38 		break;
39 	case 5:
40 		pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
41 		pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
42 		break;
43 	default:
44 		return -1;
45 	}
46 
47 	return 0;
48 }
49 
50 static void __init configure_uart(int port, int baud)
51 {
52 	u32 pbclk;
53 
54 	pbclk = pic32_get_pbclk(2);
55 
56 	__raw_writel(0, uart_base + U_MODE(port));
57 	__raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
58 	__raw_writel(UART_ENABLE, uart_base + U_MODE(port));
59 	__raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
60 		     uart_base + PIC32_SET(U_STA(port)));
61 }
62 
63 static void __init setup_early_console(int port, int baud)
64 {
65 	if (configure_uart_pins(port))
66 		return;
67 
68 	console_port = port;
69 	configure_uart(console_port, baud);
70 }
71 
72 static char * __init pic32_getcmdline(void)
73 {
74 	/*
75 	 * arch_mem_init() has not been called yet, so we don't have a real
76 	 * command line setup if using CONFIG_CMDLINE_BOOL.
77 	 */
78 #ifdef CONFIG_CMDLINE_OVERRIDE
79 	return CONFIG_CMDLINE;
80 #else
81 	return fw_getcmdline();
82 #endif
83 }
84 
85 static int __init get_port_from_cmdline(char *arch_cmdline)
86 {
87 	char *s;
88 	int port = -1;
89 
90 	if (!arch_cmdline || *arch_cmdline == '\0')
91 		goto _out;
92 
93 	s = strstr(arch_cmdline, "earlyprintk=");
94 	if (s) {
95 		s = strstr(s, "ttyS");
96 		if (s)
97 			s += 4;
98 		else
99 			goto _out;
100 
101 		port = (*s) - '0';
102 	}
103 
104 _out:
105 	return port;
106 }
107 
108 static int __init get_baud_from_cmdline(char *arch_cmdline)
109 {
110 	char *s;
111 	int baud = -1;
112 
113 	if (!arch_cmdline || *arch_cmdline == '\0')
114 		goto _out;
115 
116 	s = strstr(arch_cmdline, "earlyprintk=");
117 	if (s) {
118 		s = strstr(s, "ttyS");
119 		if (s)
120 			s += 6;
121 		else
122 			goto _out;
123 
124 		baud = 0;
125 		while (*s >= '0' && *s <= '9')
126 			baud = baud * 10 + *s++ - '0';
127 	}
128 
129 _out:
130 	return baud;
131 }
132 
133 void __init fw_init_early_console(void)
134 {
135 	char *arch_cmdline = pic32_getcmdline();
136 	int baud, port;
137 
138 	uart_base = ioremap(PIC32_BASE_UART, 0xc00);
139 
140 	baud = get_baud_from_cmdline(arch_cmdline);
141 	port = get_port_from_cmdline(arch_cmdline);
142 
143 	if (port == -1)
144 		port = EARLY_CONSOLE_PORT;
145 
146 	if (baud == -1)
147 		baud = EARLY_CONSOLE_BAUDRATE;
148 
149 	setup_early_console(port, baud);
150 }
151 
152 void prom_putchar(char c)
153 {
154 	if (console_port >= 0) {
155 		while (__raw_readl(
156 				uart_base + U_STA(console_port)) & UART_TX_FULL)
157 			;
158 
159 		__raw_writel(c, uart_base + U_TXR(console_port));
160 	}
161 }
162